Such transmissions may be built in particular in bicycles and ensure an amplification of the torque through the force applied by the bicycle rider. In this application, the housing of the transmission is adapted to a frame component and the force transmission means, such as a toothed ring, transmits the torque generated by the bicycle rider via a chain to the rear wheel. However, the transmission according to the invention may likewise be provided, for example, for wind power plants with vertically placed axles of rotation.
A prior art of this kind is formed by DE 10 2010 033 211 B4 with a bicycle transmission, in which the sun wheel, the planet gear and the crank are arranged inside a common crank housing and the crank arm is braced by means of a guide roller against a guide rail likewise arranged in the crank housing. The crank engages on two sides with a head of the crank arm and thereby takes up any tilting moments present. The guide roller, on the other hand, runs freely against the guide rail, or else the mounting of the crank arm head would be over constrained. It has proven to be a drawback in the known transmission that the pedaling is felt as being spongy on account of the free running guide roller and furthermore the known design with a crank arm head mounted on two sides results in a large Q-factor. The Q-factor in a bicycle designates the lateral distance of the outer surfaces of the two pedal cranks from each other. The larger the Q-factor, the further apart are the pedals. This increases the risk on tight curves taken at high speed that the inside pedal will touch down, and too large a Q-factor is harmful for ergonomic reasons. Also in other fields of technology it is desirable to realize a transmission of the most compact possible design in the axial direction of the main shaft.